Magnetism and Electricity

Daniel Miranian
Period-7
Journal 4-5

I. I found out that the standard deviation is the square root of the variance. The equation for standard deviation is σ= ((Σ(x-"x-bar")²)/N)½ . This equation means you take the sum of all of the individual points (x) subtracted by mean value of x (x-bar). Before you do the sum of all of these numbers you have to square each number you get so you get rid of any negative numbers. Then you divide whatever sum you get by the total number of points you have (N). If you stopped here you would get the variance. However, if you take the square root of this you get the standard deviation. Standard deviation is very useful in determining if your data is statistically significant or just random scatter. However, a calculator will easily do the equation for standard deviation for you.

II. Two weeks ago in class we continued to do exercises that highlighted principles of electricity. One day we did a Castle activity that went over which way electricity flowed. We tested this by running a current across a compass. It seemed that when the total power from the battery source was kept constant then the lower the resistance of the wire the more the compass needle would move in relationship to the wire. When we did this in class it seemed like we had a lot of outside interference from other electrical sources such as the computer and possibly the lights. However, we were able to notice a change in the needle of the compass when the wire had a current flowing through it. We also talked about how a capacitor works. I thought this was very interesting. Before this year in physics I had never heard the term capacitor, but I had seen them work before in such things as the flash of a camera.

III. For next week I would like to find out who invented the capacitor and how.